Barriers can take a variety of forms, such as gates, garage doors, or retractable barriers that protrude or retract from below ground, or slide or otherwise move from above or from the side of an opening such as a door, hallway, driveway, or other route of passage.
Barriers may be opened using a variety of methods. A barrier may be simply pushed opened manually. Mechanized barriers may be opened by pressing a control device such as a button or lever that activates a motor or other device. Garages doors and gates can currently be opened via remote control devices that are carried by a person or stored in a car.